Tuesday, December 01, 2015

Working with the light

Those of you who have looked at my pictures from the Auditorium will have noticed how harsh the lighting is in there. The directional spotlights bleach out people's faces and at the same time cast very dark shadows. To be fair, it is pretty much the same in any concert venue.

One solution to the problem is to use flash but a) that is so intrusive during a concert b) you need to be close up for it to work and c) it also bleaches out subject that are close whilst throwing further subjects into shadow.

I normally try and sit at the back of the first section so that I can see the whole of the band and point my camera at different parts. I use a 70-200mm lens on a full frame camera and sometimes add a 1.4x extender to give me more reach.

If you were to look at the information about my photos, you would see that they are mostly taken at full aperture for that lens i.e. f2.8 and shutter speeds are nominally 1/120th of a second. At 200mm that would give me many blurred shots but for the incredible image stabilisation system of the Canon lens.

In the Auditorium I set what is called exposure compensation to bring the exposure as far into the highlights as I can without losing them into solid white. In photography speak that is "exposing to the right" because the highlights are shown on the right side of a histogram of light. "Clipped" highlights are impossible to recover whatever wizardry you try to perform later on a computer.

At those settings, I then allow the camera to choose an appropriate ISO (film speed in old parlance) to get correct exposure. In my days with film, 400 ISO was the highest speed you could buy. You had to what was called push process it to get speeds up to 1,600 ISO and the result was then very grainy.

These days digital cameras have a range of ISO speeds up to 100,000 and more. As the speed increases so does the digital noise and with noise you lose precious detail in a multicoloured blotchy mess. Looking at the speeds that my camera has chosen shows the range to be from 1,500 to about 5,000 ISO and sometimes even 6,400.

When I process the pictures in my computer there are several things that I do. First of all I correct the colour to try and bring it close to neutral. Then I reduce any noise without losing too much detail. I crop my photos to achieve a better composition and finally I try and bring back some of lost information in the shadows.

Therein lies a problem though because what I am relying upon is wide dynamic range from my sensor i.e. its ability to record detail in shadows and highlights at the same time. Dynamic range of digital sensors is always at its highest at the lower ISO settings e.g. ISO 100 and progressively gets lower as the sensitivity increases. At 3,200 ISO it is at its lowest.

These days, the cameras with the greatest dynamic range are those that use Sony sensors which includes Nikons. Canon are lagging behind in this area of design. On the latest Sony sensors you can find detail in areas that appear totally black on first sight - quite remarkable.

To make matters worse, Canon sensors also suffer from banding at low ISO settings. Banding occurs when you try to lighten shadows and show up as colour streaks across those areas. Fortunately, banding is not a problem at the higher ISO settings I use in the Auditorium.

So why did I not chose to go with Nikon? Well, when I first bought a full frame camera, the Canon 5D MkII seemed to have a better feature set than the Nikon D700 which was its competitor. Once I had lenses and flashguns to go with the camera, I was pretty much locked into the Canon system and it would cost me a small fortune to change now. In any case, we Canon shooters live in hope that new versions of their cameras will catch up and hopefully surpass Nikon and then we will be the ones with smiles on our faces.

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